U.S. patent number 7,777,608 [Application Number 11/844,978] was granted by the patent office on 2010-08-17 for secure cargo transportation system.
This patent grant is currently assigned to Round Rock Research, LLC. Invention is credited to Benjamin G. Bates.
United States Patent |
7,777,608 |
Bates |
August 17, 2010 |
Secure cargo transportation system
Abstract
One embodiment provides a wireless communications device
comprising a processing unit; a location-determining subsystem
communicatively coupled to the processing unit, the
location-determining subsystem to determine a current location of
the wireless communications device using a global positioning
system (GPS); a first wireless communications subsystem coupled to
the processing unit, the first wireless communications subsystem to
communicate location information using a cellular communications
system; and a second wireless communications subsystem coupled to
the processing unit, the second wireless communications subsystem
to modulate a radio frequency (RE) field provided by a remote
interrogator to wirelessly provide a random number generated on the
wireless communications device as an identifier of the wireless
communications device; wherein the second wireless communications
subsystem is switchable between transmitting in a passive mode and
transmitting in an active mode.
Inventors: |
Bates; Benjamin G. (Boise,
ID) |
Assignee: |
Round Rock Research, LLC (Mt.
Kisco, NY)
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Family
ID: |
25430053 |
Appl.
No.: |
11/844,978 |
Filed: |
August 24, 2007 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20070285213 A1 |
Dec 13, 2007 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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11890051 |
Aug 3, 2007 |
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11037774 |
Aug 7, 2007 |
7253715 |
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10903851 |
Feb 28, 2006 |
7005961 |
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10452969 |
Aug 10, 2004 |
6774762 |
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09516634 |
Jun 24, 2003 |
6583713 |
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08911303 |
May 2, 2000 |
6057779 |
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Current U.S.
Class: |
340/7.29;
340/5.5; 340/7.25; 340/5.73; 340/539.13; 340/5.21 |
Current CPC
Class: |
G07C
9/00896 (20130101); G07C 9/00309 (20130101); G07C
9/33 (20200101); G07C 5/008 (20130101); G07C
9/28 (20200101); G06Q 50/28 (20130101); G07C
9/00912 (20130101); G07C 2209/63 (20130101); G07C
2009/00825 (20130101); G07C 2009/0092 (20130101) |
Current International
Class: |
G08B
5/22 (20060101) |
Field of
Search: |
;340/5.73,5.21,10.31,7.25,825.69 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
USPTO, Transaction History for U.S. Appl. No. 08/911,303, filed
Aug. 14, 1997, entitled "Method of Controlling Access to a Movable
Container and to a Compartment of a Vehicle and a Secure Cargo
Transportation System," now U.S. Patent No. 6,057,779. cited by
other .
USPTO, Transaction History for U.S. Appl. No. 09/516,634, filed
Mar. 1, 2000, entitled "Method of Controlling Access to a Movable
Container and to a Compartment of a Vehicle and a Secure Cargo
Transportation System," now U.S. Patent No. 6,583,713. cited by
other .
USPTO, Transaction History for U.S. Appl. No. 10/452,969, filed
Jun. 2, 2003, entitled "Secure Cargo Transportation System," now
U.S. Patent No. 6,774,762. cited by other .
USPTO, Transaction History for U.S. Appl. No. 10/903,851, filed
Jul. 30, 2004, entitled "Secure Cargo Transportation System," now
U.S. Patent No. 7,005,961. cited by other .
USPTO, Transaction History for U.S. Appl. No. 11/037,774, filed
Jan. 18, 2005, entitled "Secure Cargo Transportation System," now
U.S. Patent No. 7,253,715. cited by other .
USPTO, Transaction History for U.S. Appl. No. 11/890,051, filed
Aug. 3, 2007, entitled "Wireless Communications Devices, Wireless
Communications Systems, and Methods of Performing Wireless
Communications With a Portable Device." cited by other .
USPTO, Transaction History for U.S. Appl. No. 11/844,974, filed
Aug. 24, 2007, entitled "Secure Cargo Transportation System." cited
by other .
USPTO, Transaction History for U.S. Appl. No. 11/844,976, filed
Aug. 24, 2007, entitled "Secure Cargo Transportation System." cited
by other .
Chartered Semiconductor Manufacturing, "Toppan Announces Volume
Production of Next Generation RFID Chip," press release, Jul. 8,
2003. cited by other .
Sakamura, Ken, "TRON News Items for Jan. 2004," located at
http://tronweb.super-nova.co.jp/tronnews04-1. html. cited by other
.
Tuttle, John R., U.S. Appl. No. 08/806,158, filed Feb. 25, 1997,
now abandoned. cited by other .
Peng, Chen et al., "The Analysis and Design of a Novel Passive
Reflection Modulation Tag," IEEE Proceedings of the 4th
International Conference on Microwave and Millimeter Wave
Technology, pp. 402-405, Aug. 2004. cited by other .
Turner, Chris, "Backscatter Modulation of Impedance Modulated RFID
Tags," located at
www.rfip.eu/backscatter.sub.--tag.sub.--link.sub.--budget.sub.--and.sub.--
-modulation.sub.--at.sub.--reader.sub.--receiver.pdf, Feb. 2003.
cited by other .
Tuttle, John R., "Digital RF/ID Enhances GPS," Proceedings of the
Second Annual Wireless Symposium, Feb. 1994, pp. 406-411. cited by
other .
Intellikey Corporation Web Page, Mar. 3, 1997. cited by
other.
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Primary Examiner: Brown; Vernal U
Attorney, Agent or Firm: Greenberg Traurig, LLP
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This is a continuation of U.S. patent application Ser. No.
11/890,051, filed Aug. 3, 2007, which in turn is a continuation of
U.S. patent application Ser. No. 11/037,774, filed Jan. 18, 2005,
now U.S. Pat. No. 7,253,715, which in turn is a continuation of
U.S. patent application Ser. No. 10/903,851, filed Jul. 30, 2004,
now U.S. Pat. No. 7,005,961, which in turn is a continuation of
U.S. patent application Ser. No. 10/452,969, filed Jun. 2, 2003,
now U.S. Pat. No. 6,774,762, which in turn is a continuation of
U.S. patent application Ser. No. 09/516,634, filed Mar. 1, 2000,
now U.S. Pat. No. 6,583,713, which in turn is a continuation of
U.S. patent application Ser. No. 08/911,303, filed Aug. 14, 1997,
now U.S. Pat. No. 6,057,779, all of which are incorporated herein
by reference.
Claims
What is claimed is:
1. A wireless communications device, comprising: a processing unit;
a location-determining subsystem communicatively coupled to the
processing unit, the location-determining subsystem to determine a
current location of the wireless communications device using a
global positioning system (GPS); a first wireless communications
subsystem coupled to the processing unit, the first wireless
communications subsystem to communicate location information using
a cellular communications system; and a second wireless
communications subsystem coupled to the processing unit, the second
wireless communications subsystem to modulate a radio frequency
(RF) field provided by a remote interrogator to wirelessly provide
a random number generated on the wireless communications device as
an identifier of the wireless communications device; wherein the
second wireless communications subsystem is switchable between
transmitting in a passive mode and transmitting in an active
mode.
2. The wireless communications device of claim 1, wherein the first
wireless communications subsystem comprises a cellular
communications device controlled by the processing unit to perform
wireless communications with the cellular communications system;
and the second wireless communications subsystem comprises an
identification device to generate the random number and to modulate
the RF field.
3. The wireless communications device of claim 2, wherein the
cellular communications device comprises a cellular receiver
coupled to a first antenna for wireless communications with the
cellular communications system; and the identification device is
coupled to a second antenna to provide identification information
comprising the random number.
4. The wireless communications device of claim 3, wherein the
second antenna comprises at least one loop.
5. The wireless communications device of claim 4, wherein the
identification device comprises a transmitter switchable between
transmitting using a carrier provided by an interrogator and
transmitting using a carrier generated by the wireless
communications device.
6. The wireless communications device of claim 2, wherein the
identification device comprises a transmitter switchable between a
first mode in which the transmitter modulates an RF field generated
by the remote interrogator and a second mode in which the
transmitter modulates an RF field generated by the identification
device.
7. The wireless communications device of claim 6, wherein the
identification information is transmitted via magnetic field
modulation.
8. The wireless communications device of claim 1, wherein the
location-determining subsystem comprises a GPS receiver; and the
first wireless communications subsystem comprises a cellular
receiver coupled to the processing unit.
9. The wireless communications device of claim 8, wherein the
location information is received at the wireless communications
device via the first wireless communications subsystem.
10. The wireless communications device of claim 1, wherein the
second wireless communications subsystem is to wirelessly provide a
unique identification code via modulating a radio frequency (RF)
field provided by the remote interrogator.
11. A portable device, comprising: a processing unit; a
location-determining system coupled to the processing unit, the
location-determining system to determine a current location of the
portable device using a global positioning system (GPS); a memory
to log locations determined by the location-determination system
with respect to time; a first antenna; a cellular communications
device coupled to the processing unit and the first antenna, the
cellular communications device to communicate location information
via the first antenna using a cellular communications system; a
second antenna; and an identification device coupled to the
processing unit and the second antenna, the identification device
to generate a random number as an identifier of the portable device
and to provide the random number, via the second antenna in a
passive mode of operation, by modulating a radio frequency (RF)
field provided by an interrogator wirelessly coupled to the
identification device; wherein in an active mode of operation the
identification device is to provide an RF field for
communications.
12. The portable device of claim 11, wherein the identification
device is to provide a unique identifier, in addition to the random
number, via the second antenna in the passive mode of
operation.
13. The portable device of claim 11, wherein the
location-determining system comprises a GPS receiver; and the
cellular communications device comprises a cellular receiver.
14. A wireless communications device, comprising: a processing
unit; a location-determining subsystem communicatively coupled to
the processing unit, the location-determining subsystem to
determine a current location of the wireless communications device
using a global positioning system (GPS); a first wireless
communications subsystem coupled to the processing unit, the first
wireless communications subsystem to communicate identification
information using a cellular communications system; and a second
wireless communications subsystem coupled to the processing unit,
the second wireless communications subsystem to modulate a radio
frequency (RF) field provided by a remote interrogator to
wirelessly provide a random number generated on the wireless
communications device as an identifier of the wireless
communications device; wherein the second wireless communications
subsystem comprises a transmitter switchable between a first mode
in which the transmitter modulates the RF field generated by the
remote interrogator and a second mode in which the transmitter
modulates an RF field generated by the identification device.
15. The wireless communications device of claim 14, wherein the
identification information comprises a unique identification code
to identify the wireless communications device.
16. The wireless communications device of claim 14, wherein the
location-determining subsystem comprises a GPS receiver; the first
wireless communications subsystem comprises a cellular
communications device controlled by the processing unit to perform
wireless communications with the cellular communications system;
and the second wireless communications subsystem comprises an
identification device to generate the random number and to transmit
the random number via magnetic field modulation.
17. The wireless communications device of claim 16, wherein the
cellular communications device comprises a cellular receiver
coupled to a first antenna for wireless communications with the
cellular communications system; the identification device is
coupled to a second antenna to provide the random number; and the
second antenna comprises at least one loop.
Description
TECHNICAL FIELD
The invention relates to transportation systems. The invention also
relates to security systems, lock systems, and access control.
BACKGROUND OF THE INVENTION
Valuable cargo is transported on a daily basis. It is desirable to
secure the cargo against unauthorized access, so as to prevent
tampering, theft of some cargo, or theft of all cargo.
Cargo is typically secured using conventional locks, such as
padlocks, which are opened using a metal key. For example, for
cargo transported by semi-trailers, the cargo is typically secured
by locking the trailer door with a padlock. The driver then carries
the key.
A problem with conventional methods of securing cargo is that the
driver has access to the cargo and has the opportunity to steal
some or all of the cargo. Further, there is the possibility of the
driver being hijacked, and the key taken from the driver. There is
also the possibility of the driver diverging from the intended
course and taking the cargo to a non-approved area, such as to a
competitor, to another state or country, or through an area where
the risk of theft is greater.
While the invention was motivated in addressing the above issues,
it is in no way so limited. The invention is only limited by the
accompanying claims as literally worded, without interpretative or
other limiting reference to the specification, and in accordance
with the doctrine of equivalents.
SUMMARY
One embodiment provides a wireless communications device comprising
a processing unit; a location-determining subsystem communicatively
coupled to the processing unit, the location-determining subsystem
to determine a current location of the wireless communications
device using a global positioning system (GPS); a first wireless
communications subsystem coupled to the processing unit, the first
wireless communications subsystem to communicate location
information using a cellular communications system; and a second
wireless communications subsystem coupled to the processing unit,
the second wireless communications subsystem to modulate a radio
frequency (RE) field provided by a remote interrogator to
wirelessly provide a random number generated on the wireless
communications device as an identifier of the wireless
communications device; wherein the second wireless communications
subsystem is switchable between transmitting in a passive mode and
transmitting in an active mode.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention are described below with
reference to the following accompanying drawings.
FIG. 1 is a perspective view illustrating a secure cargo
transportation system and a method for controlling access to a
movable container.
FIG. 2 is a diagrammatical perspective view illustrating a lock,
controller, and key included in the system of FIG. 1.
FIG. 3 is a block diagram illustrating the system of FIG. 1 in
communication with a central communications station.
FIG. 4 is a block diagram of an interrogator or transmitter
included in the central station of FIG. 3.
FIG. 5 is a block diagram showing details of DPSK circuitry
included in the interrogator of FIG. 4.
FIG. 6 is a block diagram showing details of RF circuitry included
in the interrogator of FIG. 4.
FIGS. 7 and 8 together define a flowchart illustrating operation of
the secure cargo transportation system of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
This disclosure of the invention is submitted in furtherance of the
constitutional purposes of the U.S. Patent Laws "to promote the
progress of science and useful arts" (Article 1, Section 8).
FIG. 1 shows a secure cargo transportation system 10 embodying the
invention. The secure cargo transportation system 10 comprises a
movable container or vehicle 12 including an enclosure 14 having an
opening 16. In the illustrated embodiment, the vehicle 12 is a semi
trailer. In alternative embodiments, the movable container is
defined by a train boxcar, a safe, a compartment in a boat or
plane, or any other movable container. The vehicle 12 includes a
door 18 movable relative to the opening 16 between a closed
position, wherein the door 18 restricts access to the enclosure,
and an open position (FIG. 2). In some embodiments, the vehicle
includes multiple doors 18, 20. The vehicle 12 includes an
electronically actuable lock 22 to selectively lock or unlock the
door relative to the enclosure. In embodiments having two doors,
the primary door is locked with an electronically enabled or
actuable lock 22, or both doors are locked with an electronically
enabled or actuable lock 22 such that access to the enclosure
requires unlocking at least one electronically actuable lock
22.
More particularly, in the preferred embodiment, the doors 18 and 20
are fitted with an intelligent lock controller such as the lock
controller sold by Intellikey Corporation, 551 S. Apollo Blvd.,
#204, Melbourne, Fla. 32901. In one embodiment, pre-existing
mechanical cylinders can be replaced with electronic cylinders of
the type sold by Intellikey, or the electronic cylinders can be
installed initially. An electronic controller 24 is supported by
the back of the door, inside the enclosure 14, or in other
appropriate (preferably secure) location. In the illustrated
embodiment, the lock 22 requires both an electronic key or signal
and a mechanical key to open the lock. More particularly, a key 26
has a mechanical portion 28 as well as circuitry 30 supported
therefrom (e.g., in the handle for the key) which communicates
electronically with the lock (e.g., by radio frequency or magnetic
coupling). In alternative embodiments, only an electronic key or
signal is required to open the lock. Data communicated between the
key and lock is encrypted, in the illustrated embodiment. In the
illustrated embodiment, the key and lock provide multiple levels of
access. For example, in the illustrated embodiment, seven
masterkeying levels are available. The electronic controller 24 can
be programmed to change whose key will open the lock and when. The
circuitry 30 of the key 26 includes memory which carries access
control information and identifying information for the user of the
key. The controller 24 reads this information and determines
whether the user of the key should be granted access. The
controller 24 is programmable to grant access to the user of the
key based on factors such as location and time. The memory of the
circuitry 30 records an audit trail of in which lock the associated
key 26 has been used. In addition to the electronic controller 24
being programmable, the circuitry 30 of the key 26 is also
programmable, and access control and feature information can be
changed for each key using a key programming unit available from
Intellikey Corporation.
The system 10 further includes a remote intelligent communications
device 32 (FIG. 3) supported by the vehicle 12 and in communication
with the lock 22. More particularly, in the illustrated embodiment,
the remote intelligent communications device 32 has an RS-232 port,
and communicates with the lock controller 24 via a RS-232 cable
connected between the RS-232 port of the device 32 and the lock
controller 24. The remote intelligent communications device 32
includes a processor 33, a memory 34 coupled to the processor 33,
and a global positioning system receiver 36 in communications with
the processor 33, and thus with the memory 34. The global
positioning system receiver 36 communicates with a global
positioning satellite 37 to determine the position of the receiver
36. While other embodiments are possible, in the illustrated
embodiment, the global positioning system receiver 36 is an
Encore.TM. GPS receiver manufactured by or available from Motorola
Inc., Schaumburg, Ill. The remote intelligent communications device
32 periodically or at various times logs in the memory 34 the
position of the device 32 (and therefore the position of the
vehicle 12) with respect to time. The remote intelligent
communications device 32 uses UTC time obtained from GPS satellite
data to provide time of day information for use with the logging of
the position information.
An exemplary remote intelligent communications device 32 that can
be employed is described in commonly assigned U.S. patent
application Ser. No. 08/656,530, titled "A Method And Apparatus For
Remote Monitoring," (now U.S. Pat. No. 5,894,266) incorporated
herein by reference. In the preferred embodiment, the remote
intelligent communications device 32 is an Ambit.TM. remote
intelligent communications device available from Micron
Communications, Boise, Id. The Ambit.TM. device is a board level
device which is similar in design and operation to an integrated
circuit described in commonly assigned U.S. patent application Ser.
No. 08/705,043, filed Aug. 29, 1996 (now U.S. Pat. No. 6,130,602),
and incorporated herein by reference, except that it further
includes the global positioning system receiver.
The remote intelligent communications device 32 further includes a
radio frequency (RF) communications receiver 38 coupled to the
processor 33, which receives a desired location coordinate at which
access to the contents of the enclosure 14 is permitted. The remote
intelligent communications device 32 further includes a radio
frequency (RF) communications transmitter 39 coupled to the
processor 33. In the illustrated embodiment, the remote intelligent
communications device receives and transmits data at microwave
frequencies. The remote intelligent communications device includes
indicia for uniquely identifying the vehicle 12 with respect to
other vehicles 12. A central station 46 can communicate with a
specified vehicle 12 out of a fleet of vehicles 12, 12b. More
particularly, in the illustrated embodiment, multiple vehicles are
equipped with the remote intelligent communications device 32 and
lock 22, and the central station 46 can communicate with any
desired vehicles to control access to enclosure 14 of a specified
vehicle.
Desired access locations, such as docking bays 42 at final
destinations are determined by a responsible person 44 at a central
station 46 and communicated to the vehicle 12, such as by using a
transmitter 49 (described below) located at or controlled at the
central station 46.
When the vehicle 12 enters into a specified area, as determined by
the GPS receiver 36, the remote intelligent communications device
32 sends a digital message to the controller 24 enabling the lock
22 to be opened with the key 26. The GPS area is defined so as to
take into account the error possible with the GPS receiver 36 being
used. The receiver 38 receives commands from the transmitter 49
when in communications range with a transmitter.
A desired or specified location 48 received by the receiver 38 is
stored in memory. For example, the receiver receives a point and a
radius, or three geographic points to define a desired area or
location, or two points to define a line and an offset distance to
the left and right of the line. In one embodiment, the processor 33
provides a signal to the controller 24 of the lock to enable
unlocking using the key 26 if the vehicle 12 is within a
predetermined distance of the desired location. Multiple locations
can be specified where access is permitted. In another embodiment,
the processor 33 provides for exception logic, enabling unlocking
in all areas except a specified location 48.
Other methods of receiving and storing location coordinates can be
employed. For example, some coordinates can be pre-programmed. For
example, weigh stations at state lines have known coordinates which
can be stored in memory so unlocking is enabled at these
locations.
Further, new location coordinates where access is permitted can be
communicated to the device 32 by a paging network or system 50. To
this end, the device 32 further includes a paging receiver 52
coupled to the processor 33. Emergency access to the contents of
the enclosure 14 can be granted by the operator 44 using the paging
system. For example, if the vehicle is stopped by police who want
to inspect cargo in the enclosure 14, the driver of the vehicle,
using a telephone 54, can call a telephone 56 manned by the
operator 44 at the central station 46. The operator 44 can then
authorize access, regardless of the vehicle's location, using the
same or a different telephone 58 to access the paging system 50.
The telephone 54 used by the driver can be a cellular phone on
board the vehicle, or a pay phone or other phone located outside
the vehicle 12.
Alternatively, a cellular receiver can be employed instead of the
paging receiver.
In one embodiment, a plurality of geographical areas 60 through
which it is desired that the vehicle 12 travel are stored in memory
34. The geographical location of the container at each of a
plurality of different times is logged, and the locking mechanism
22 is enabled to permit unlocking if the vehicle 12 passed through
all of the geographical areas stored in memory 34.
In another embodiment of the invention, an order of geographical
areas is defined, and the locking mechanism 22 is enabled to permit
unlocking if the vehicle passed through the geographical areas in
the defined order.
In another embodiment, an order of geographical areas is defined,
including a final destination geographical area (e.g., area 48),
and the locking mechanism 22 is enabled to unlock if the vehicle 12
passed through each of the geographical areas 60 in the defined
order and is in the final destination geographical area.
In another embodiment of the invention, data defining a desired
path of travel through which it is desired that the container
travel is stored in memory 34. A geographical area defining a
desired final destination (e.g., area 48) is also stored in memory
34. An alert signal is produced if the vehicle 12 deviates from the
desired path of travel. In one aspect of the invention, data is
stored defining a plurality of overlapping geographical areas. In
one embodiment, the device 32 is coupled to the electrical system
of the vehicle 12, or to an engine controller of the vehicle 12,
and cuts off the engine if the vehicle deviates from the desired
path of travel by more than a programmed amount. For example, the
device 32 can be coupled to the engine controller in the manner
disclosed in commonly assigned U.S. patent application Ser. No.
08/759,737, filed Dec. 6, 1996 (now U.S. Pat. No. 5,995,898) and
incorporated herein by reference.
As previously mentioned, the central station 46 includes the
transmitter 49. More particularly, in the illustrated embodiment,
the central station 46 includes an interrogator 47 comprising the
transmitter 49, and further comprising a receiver 51. The remote
intelligent communications device 32 transmits and receives radio
frequency communications to and from the interrogator 47. The
central station 46 further includes one or more send/receive
antenna pairs 62 coupled to the interrogator 47. In an alternative
embodiment, the interrogator 47 uses an antenna both for
transmitting and receiving by the interrogator 47. The interrogator
47 includes transmitting and receiving circuitry, similar to that
implemented in the remote intelligent communication device 32. In
one embodiment, the system central station 46 further includes a
controller 64. In the illustrated embodiment, the controller 64 is
a computer. The controller 64 acts as a master in a master-slave
relationship with the interrogator 47. The controller 64 includes
an applications program for controlling the interrogator 47 and
interpreting responses, and a library of radio frequency
identification device applications or functions as described in the
above-incorporated patent applications. Most of the functions
communicate with the interrogator 47. These functions effect radio
frequency communication between the interrogator 47 and the remote
intelligent communications device 32. In one embodiment, the
controller 64 and the interrogator 47 are combined together (e.g.,
in a common housing), or functions of the host computer are
implemented in hard wired digital logic circuitry.
Generally, the interrogator 47 transmits an interrogation signal or
command, such as a command to add geographical locations where
opening of the lock 22 is enabled, ("forward link") via one of the
antennas 62. The remote intelligent communications device 32
receives the incoming interrogation signal via its antenna, if it
is within receiving range. Upon receiving the signal, the remote
intelligent communications device 32 responds by generating and
transmitting a responsive signal or reply ("return link"). The
interrogator 47 is described in greater detail below.
In the illustrated embodiment, signals transmitted and received by
the interrogator 47, and signals transmitted and received by the
remote intelligent communications device 32 are modulated spread
spectrum signals. Many modulation techniques minimize required
transmission bandwidth. However, the spread spectrum modulation
technique employed in the illustrated embodiment requires a
transmission bandwidth that is up to several orders of magnitude
greater than the minimum required signal bandwidth. Although spread
spectrum modulation techniques are bandwidth inefficient in single
user applications, they are advantageous where there are multiple
users (e.g., multiple vehicles 12, 12b). The spread spectrum
modulation technique of the illustrated embodiment is advantageous
because the interrogator signal can be distinguished from other
signals (e.g., radar, microwave ovens, etc.) operating at the same
frequency. The spread spectrum signals transmitted by the device 32
and by the interrogator 47 are pseudo random and have noise-like
properties. A spreading waveform is controlled by a pseudo-noise or
pseudo random number (PN) sequence or code. The PN code is a binary
sequence that appears random but can be reproduced in a
predetermined manner by the device 32. More particularly, incoming
spread spectrum received by the device 32 or interrogator 47 are
demodulated through cross correlation with a version of the pseudo
random carrier that is generated by the device 32 itself or the
interrogator 47 itself, respectfully. Cross correlation with the
correct PN sequence unspreads the spread spectrum signal and
restores the modulated message in the same narrow band as the
original data.
A pseudo-noise or pseudo random sequence (PN sequence) is a binary
sequence with an autocorrelation that resembles, over a period, the
autocorrelation of a random binary sequence. The autocorrelation of
a pseudo-noise sequence also roughly resembles the autocorrelation
of band-limited white noise. A pseudo-noise sequence has many
characteristics that are similar to those of random binary
sequences. For example, a pseudo-noise sequence has a nearly equal
number of zeros and ones, very low correlation between shifted
versions of the sequence, and very low cross correlation between
any two sequences. A pseudo-noise sequence is usually generated
using sequential logic circuits. For example, a pseudo-noise
sequence can be generated using a feedback shift register.
A feedback shift register comprises consecutive stages of two state
memory devices, and feedback logic. Binary sequences are shifted
through the shift registers in response to clock pulses, and the
output of the various stages are logically combined and fed back as
the input to the first stage. The initial contents of the memory
stages and the feedback logic circuit determine the successive
contents of the memory.
The illustrated embodiment employs direct sequence spread spectrum
modulation. A direct sequence spread spectrum (DSSS) system spreads
the baseband data by directly multiplying the baseband data pulses
with a pseudo-noise sequence that is produced by a pseudo-noise
generator. A single pulse or symbol of the PN waveform is called a
"chip." Synchronized data symbols, which may be information bits or
binary channel code symbols, are added in modulo-2 fashion to the
chips before being modulated. The receiver performs demodulation.
For example, in one embodiment the data is phase modulated, and the
receiver performs coherent or differentially coherent phase-shift
keying (PSK) demodulation. In another embodiment, the data is
amplitude modulated. Assuming that code synchronization has been
achieved at the receiver, the received signal passes through a
wideband filter and is multiplied by a local replica of the PN code
sequence. This multiplication yields the unspread signal.
A pseudo-noise sequence is usually an odd number of chips long.
Spread spectrum techniques are also disclosed in the following
patent applications and patent, which are incorporated herein by
reference: U.S. patent application Ser. No. 08/092,147 (now
abandoned); U.S. patent application Ser. No. 08/424,827, filed Apr.
19, 1995 (now U.S. Pat. No. 5,790,946); and U.S. Pat. No. 5,121,407
to Partyka et al. They are also disclosed, for example, in "Spread
Spectrum Systems," by R. C. Dixon, published by John Wiley and
Sons, Inc.
In one embodiment, the interrogator 47 is coupled to the controller
64 via an IEEE-1284 enhanced parallel port (EPP).
In one embodiment, communications from the interrogator 47 to the
device 32, and communications from the device 32 to the
interrogator 47 use different physical protocols.
The physical communications protocol for communications from the
interrogator 47 to the device 32 is referred to as the "forward
link" protocol. In the illustrated embodiment, the forward link
data is sent in the following order:
Preamble
Barker Code
Command Packet
Check Sum
A Maximal Length Pseudo Noise (PN) Sequence is used in the Direct
Sequence Spread Spectrum (DSSS) communications scheme in the
forward link. In one embodiment, the sequence is generated by a
linear feedback shift register of a specified form. In the
illustrated embodiment, there are multiple registers, the output of
one of the registers is X-ORed with the output of another register,
and the result is fed into the input of the first register. This
produces a repeating 31 "chip" sequence. The sequence ends with all
registers set to one. The sequence is taken from the output of the
first register. This code is synchronous with the data in that each
data bit comprises one and only one full PN sequence.
In one embodiment, a zero bit is transmitted as one inverted full
cycle of the PN sequence. A one bit is transmitted as one full
non-inverted cycle of the PN sequence.
The preamble precedes the data. In one embodiment, the preamble
includes a series of zeros, followed by a start or Barker code.
In one embodiment, the Barker code is defined by the following bit
string: 1111 1001 1010 1. Other embodiments are of course
possible.
In the illustrated embodiment, command data is grouped into 13-bit
words. Each word includes eight data bits (D7, D6, D5, D4, D3, D2,
D1, DO) and five ECC (Error Correction Code) bits (P4, P3, P2, P1,
and PO). In one embodiment, the bit transmission order is (with D7
transmitted first):
D7, D6, D5, D4, D3, D2, D1, D0, P4, P3, P2, P1, PO . . .
In one embodiment, the ECC bits (P4-PO) are generated using the
following equations: PO=(D1+D2+D5+D7)modulo 2
P1=[(D1+D3+D4+D6)modulo 2]Complement P2=(D0+D2+D3+D6+D7)modulo 2
P3=[(D0+D4+D5+D6+D7)modulo 2]Complement
P4=(DO+D1+D2+D3+D4+D5)modulo 2.
Other methods of generating the error correction code bits are of
course possible.
In the illustrated embodiment, a 16-bit check sum is provided to
detect bit errors on the packet level. The device 32 can be
programmed to either return a reply if a bad check sum is found in
the forward link, or to simply halt execution and send no replies.
In one embodiment, a 16 bit CRC is employed in the forward link,
the return link, or both, instead of or in addition to the check
sum.
The physical communications protocol for communications from the
device 32 to the interrogator 47 is referred to as the "return
link" protocol. In the illustrated embodiment, the return link
messages are sent in the following order:
Preamble,
Barker Code,
Reply Packet
Check Sum
After sending a command, the interrogator 47 sends a continuous
unmodulated RF signal with a specified frequency, such as 2.44 GHz,
915 MHz, or other frequencies. In the illustrated embodiment,
return link data is Differential Phase Shift Key (DPSK) modulated
onto a square wave subcarrier with a frequency of 596.1 kHz. A data
0 corresponds to one phase and data 1 corresponds to another,
shifted 180 degrees from the first phase. For a simple dipole, a
switch between the two halves of the dipole antenna is opened and
closed. When the switch is closed, the antenna becomes the
electrical equivalent of a single half-wavelength antenna that
reflects a portion of the power being transmitted by the
interrogator. When the switch is open, the antenna becomes the
electrical equivalent of two quarter-wavelength antennas that
reflect very little of the power transmitted by the
interrogator.
The preamble for the return link includes 2000 bits, alternating 2
zeros then 2 ones, etc., and a 13-bit start (Barker) code.
Alternative preambles are possible.
In the illustrated embodiment, the start code or Barker Code is
defined by the following bit string: 1111 1001 1010 1.
The reply link data is grouped in 13 bit words. Each word is
composed of 8 data bits (D7, D6, D5, D4, D3, D2, D1, DO) and 5 ECC
bits (P4, P3, P2, P1, PO).
The Block Encoded Sequence is D7, D6, D5, D4, D3, D2, D1, D0, P4,
P3, P2, P1, PO.
The Block ECC Bits (P4-PO) are generated using the following
equations: PO=(D1+D2+D5+D7)modulo 2 P1=[(D1+D3+D4+D6)modulo
2]Complement P2=(D0+D2+D3+D6+D7)modulo 2 P3=[(D0+D4+D5+D6+D7)modulo
2]Complement P4=(DO+D1+D2+D3+D4+D5)modulo 2.
Other methods of generating error correction code bits can, of
course, be employed.
In the illustrated embodiment, a 16-bit check sum is provided to
detect bit errors on the packet level. In one embodiment, a 16 bit
CRC is employed in addition to or instead of the check sum.
Each pair of data words is interleaved, starting with the Barker
code and the first data word. The transmitted bit order for two
sequential words, A and B, is D7A, D7B, D6A, D6B, D5A, D5B, D4A,
D4B, D3A, D3B, D2A, D2B, D1A, D1B, DOA, DOB, P4A, P4B, P3A, P3B,
P2A, P2B, P1A, P1B, POA, POB.
D7A is the first transmitted bit. In the illustrated embodiment,
DPSK is applied to the interleaved data.
Other communications protocols are of course possible for the
forward link and return link.
Details of construction of the interrogator 47 will now be
provided, reference being made to FIG. 4. The interrogator 47
includes enhanced parallel port (EPP) circuitry 70, DPSK
(differential phase shift keyed) circuitry 72, and RF (radio
frequency) circuitry 74, as well as a power supply (not shown) and
a housing or chassis (not shown). In the illustrated embodiment,
the enhanced parallel port circuitry 70, the DPSK circuitry 72, and
the RF circuitry 74 respectively define circuit card assemblies
(CCAs). The interrogator 47 uses an IEEE-1284 compatible port in
EPP mode to communicate with the controller 64. The EPP circuitry
70 provides all the digital logic required to coordinate sending
and receiving a message to and from a remote intelligent
communications device 32 of a vehicle 12. The EPP circuitry 70
buffers data to transmit from the controller 64, converts the data
to serial data, and encodes it. The EPP circuitry 70 then waits for
data from the device 32, converts it to parallel data, and
transfers it to the controller 64. In one embodiment, messages
include a programmable number of bytes of data.
The EPP mode interface provides an asynchronous, interlocked, byte
wide, bi-directional channel controlled by the controller 64. The
EPP mode allows the controller 64 to transfer, at high speed, a
data byte to/from the interrogator within a single host computer
CPU I/O cycle (typically 0.5 microseconds per byte).
The DPSK circuitry 72 (see FIG. 5) receives signals I and Q from
the RF circuitry 74 (described below), which signals contain the
DPSK modulated sub-carrier. The DPSK circuitry 72 includes
anti-aliasing filters 76 and 78 filtering the I and Q signals,
respectively, and analog to digital (A/D) converters 80 and 82
respectively coupled to the filters 76 and 78 and respectively
converting the filtered signals from analog to digital signals. The
DPSK circuitry 72 further includes a combiner 84, coupled to the
A/D converters 80 and 82, combining the digital signals. The DPSK
circuitry 72 further includes a FIR matched filter 86, coupled to
the combiner 84, which filters the combined signals. The DPSK
circuitry 72 further includes delay circuitry 88 and multiplier
circuitry 90 coupled to the FIR matched filter 86 for delaying the
signal and multiplying the signal with the delayed signal to remove
the sub-carrier. The DPSK circuitry 72 further includes low pass
filter circuitry 92, coupled to the multiplier 90, filtering the
output of the multiplier 90 to remove the X2 component. The DPSK
circuitry 72 further includes a bit synchronizer 94 coupled to the
filter 92 for regeneration of the data clock. The DPSK circuitry 72
further includes lock detect circuitry 96 coupled to the low pass
filter 92 and generating a lock detect signal. The data, clock, and
lock detect signal are sent to the EPP circuitry 70.
The RF circuitry 74 (see FIG. 6) interfaces with the transmit and
receive antennas 62. The RF circuitry modulates the data for
transmission to a device 32 of a vehicle 12, provides a continuous
wave (CW) carrier for backscatter communications with a device 32
(if backscatter communications are employed), and receives and
downconverts the signal received from the transponder unit (which
is a backscatter signal in one embodiment).
The RF circuitry 74 also includes a power divider 98, and a
frequency synthesizer 100 coupled to the power divider 98. The
frequency synthesizer 100 tunes the RF continuous waver carrier for
frequency hopping and band selection. The RF circuitry defines a
transmitter, and receives data from the EPP circuitry 70. The RF
circuitry 74 includes an amplitude modulation (AM) switch 102 that
receives the data from the EPP circuitry 70 and amplitude modulates
the data onto a carrier. More particularly, the AM switch 102 turns
the RF on and off (ON OFF KEY). The RF circuitry 74 further
includes a power amplifier 104, coupled to the AM switch 102, to
amplify the signal. The RF circuitry 74 further includes a switch
106, coupled to the power amplifier 104, for transmission of the
amplified signal through a selected transmit antenna 62.
During continuous wave (CW) transmission for the backscatter mode,
the AM switch 102 is left in a closed position. When the
interrogator 50 is transmitting in the CW mode, the device 32
backscatters the signal with a DPSK modulated sub carrier. This
signal is received via one of the receive antennas 62. More
particularly, the RF circuitry 74 further includes a switch 108
coupled to the receive antennas. In another alternative embodiment,
such as when backscatter communications are not employed, the RF
circuitry uses common antennas for both transmission and reception.
The RF circuitry 74 further includes a low noise amplifier (LNA)
110 coupled to the switch 108 and amplifying the received signal.
The RF circuitry 74 further includes a quadrature downconverter
112, coupled to the LNA 110, coherently downconverting the received
signal. The RF circuitry 74 further includes automatic gain
controls (AGCs) 114 and 116 coupled to the quadrature down
converter 112. The amplitude of the signals are set using the
automatic gain controls 114 and 116 to provide the signals I and Q.
The I and Q signals, which contain the DPSK modulated sub-carrier,
are passed on to the DPSK circuitry 72 (FIG. 5) for
demodulation.
Although one interrogator 47 has been described, it may be
desirable to provide multiple interrogators along a route, or
interrogators at each of various facilities.
In one embodiment, communications between the central station 46
and a device 32 may be via the paging system 50 and paging receiver
52 or via the cellular system when the vehicle 12 is not within
communications range of an interrogator 47.
FIGS. 7 and 8 together define a flowchart illustrating operation of
the secure cargo transportation system.
In a step 120, a determination is made (e.g., by the processor 33
of the remote intelligent communications device 32) as to whether a
command has been received (e.g., from an interrogator 47 or paging
receiver 52) to add desired geographical areas. If so, the
processor proceeds to step 122; if not, the processor proceeds to
step 128.
In step 122, a desired geographical area (e.g., a point and a
radius, or three or more points) is received by the device 32.
After performing step 122, the processor proceeds to step 124.
In step 124, the desired geographical areas are stored in memory
34. After performing step 124, the processor proceeds to step
126.
In step 126, a determination is made as to whether there are
additional desired geographical areas to be stored in memory. If
so, the processor proceeds to step 122; if not, the processor
proceeds to step 128.
In step 128, a determination is made as to whether a command has
been received to change geographical areas. If so, the processor
proceeds to step 130; if not, the processor proceeds to step
136.
In step 130, the desired change is received. After performing step
130, the processor proceeds to step 132.
In step 132, the processor accesses the memory location of the
geographic area which is to be changed (or deleted). After
performing step 132, the processor proceeds to step 134.
In step 134, the processor changes (or deletes) data in the
accessed memory location, as desired. After performing step 134,
the processor proceeds to step 136.
In step 136, a determination is made as to whether a command has
been received to change a user's ability to access the container or
vehicle 12. If so, the processor proceeds to step 138; if not, the
processor proceeds to step 140.
In step 138, the device 32 communicates with the lock controller to
change a user's ability to access the container. After performing
step 138, the processor proceeds to step 140.
In step 140, the present location of the container is logged using
the GPS receiver 36. After performing step 140, the processor
proceeds to step 142.
In step 142, a determination is made as to whether the vehicle 12
or container is off course. If so, the processor proceeds to step
144; if not, the processor proceeds to step 146.
In step 144, an alarm signal is sent (e.g., an audible or visible
alarm is sent to the driver and/or to the central station 46).
After performing step 144, the processor proceeds to step 146.
In step 146, a determination is made as to whether the vehicle or
container is in a desired geographical area (e.g., the desired
final destination area). If so, the processor proceeds to step 148;
if not, the processor proceeds to step 150.
In step 148, a determination is made as to whether other
requirements for access are met (e.g., the vehicle or container is
in the desired geographic area at a specified time; the vehicle
passed through a specified sequence of desired areas; the holder of
the key 26 is a person authorized to open the lock in this area and
at this time; any other conditions imposed by the central station
46). After performing step 148, the processor proceeds to step
152.
In step 150, a determination is made as to whether an override
authorization has been received from the central station 46 (e.g.,
the vehicle is not in the desired area, but there is an emergency
situation). If so, the processor proceeds to step 152; if not, the
processor proceeds to step 120 (possibly after a time delay).
In step 152, the device 32 sends a signal to the lock 22 enabling
the lock to be opened (e.g., effecting unlocking, or permitting
unlocking using the key 26).
Thus, a method of controlling access to a movable container is
provided. As a mobile asset, such as a container, truck or some
other thing travels, its movement is recorded into the memory of
the device, with the location and movement being determined by
GPS.
The location of the vehicle will be utilized to determine
authorization keyed access to a truck. The keyed system, as tied
into the GPS, would be such that opening would be authorized when
the vehicle is within the confines of a specific location. Further,
different parts of the vehicle or container may be subjected to
different keyed openings, such that some enclosure of the vehicle
can be opened at one location, but not others.
In one embodiment, the system is programmed in a "fail safe"
manner, for example tying the ultimate access to some specific
route over which the vehicle is expected to travel. Therefore if
the truck is hijacked or the driver deviates from a prescribed
course, no opening whatsoever of the vehicle would be allowed,
absent obtaining some authorization or some other code. In other
words, the proximity within a desired route and ending locations
can be programmed into the device.
In one embodiment, when the container, truck, etc. moves in the
proximity of some general RF station, the data from the memory is
downloaded or transmitted via RF to the base unit, such that the
information is obtained and recorded remotely of the AMBIT unit on
the vehicle.
In compliance with the statute, the invention has been described in
language more or less specific as to structural and methodical
features. It is to be understood, however, that the invention is
not limited to the specific features shown and described, since the
means herein disclosed comprise preferred forms of putting the
invention into effect. The invention is, therefore, claimed in any
of its forms or modifications within the proper scope of the
appended claims appropriately interpreted in accordance with the
doctrine of equivalents.
* * * * *
References